Geochemical method



United States Patent O 3,285,698 GEOCHElVHCAL METHOD Dirk Richard Clews,Downsview, Ontario, Canada, assignor to Barringer Research Limited,Rexdale, ntario, Canada I No Drawing. Filed Apr. 26, 1962, Ser. No.191,682 8 Claims. (Cl. 23'230) The invention relates to a geochemicalmethod of prospecting for oils, gases and bituminous deposits.

Geochemical prospecting methods of various types are known in whichattempts are made .to detect the presence of underlying deposits of oiland the like by means of soil sampling. Some such methods are intendedto locate the presence of gaseous, liquid or solid hydrocarbon. Othersuch methods have been designed to locate the presence of trace elementsoriginating from such oil deposits, and attempts have been made todetect the presence of micro-organisms feeding on hydrocarbons escapingfrom such deposits. However, the majority of such methods have beendisadvantageous for various reasons; Thus, in many cases, they haveproved to be both slow and expensive in operation rendering extendedsurveys urieconomi-cal. In addition, the majority of such methods havebeen subject to considerable difficulties in interpretation and, in somecases, have produced results which have been both erroneous andmisleading. One of the more significant problems has been in connectionwith the so-called annular anomaly which has been noted'onmany occasionsand is fully'discussed in various textbooks (see for example GeochemicalMethods of- Prospecting and Exploration for Petroleum and Natural Gas,Kartsev et al., University of California Press, 1959). In this case, asporadic anomaly is located around the periphery of an oil deposit, butthe centre of the oil deposit is generally characterized by an absenceof such anomaly. Results of this type, therefore, give only aproblematical indication of the presence of a subsurface oil deposit inthe absence of other information. Intact, this result is contrary towhat would have been predicted since the strongest anomaly would beexpected over the centre of the oil deposit where the escape of gasesand liquids therefrom would normally be the strongest. Obviously, itwould be desirable to provide a geochemical prospecting method capableof achieving. continuous detection of the subsurface oil deposit 'inorder that its full extent can be plotted.

It is now suggested that the reason for the so-called annular anomaly isin fact that micro-organisms present in the earths surface over the oildeposit tend to gather over the centre of the deposit, where the escapeof gases and liquids is strongest. In addition, it is noted that thezone of oxidizing conditions in the earths surface will also tend todeepen over the centre of an oil deposit possibly due to suchmicro-organism concentration. Since the micro-organisms live on anddestroy or alter the hydrocarbon constituents, and since the strongeroxidizing conditions will tend to oxidize or alter the hydrocarbonconstituents, the methods utilizing the detection of hydrocarbonconstituents, and the methods utilizing the detection of trace elementreduction due to the escape of reducing hydrocarbon gases will detectanomalies only around the fringes of the oil deposit while detectinglittle or no anomaly towards the centre unless the sampling zone isextended downwardly beneath the zone of oxidization. However, otherconstituents such as organo trace constituents will not be so affectedand, according to one embodiment of this invention, may be detectedcontinuously across the entire extent of the oil deposit. While not alltrace constituents present in the oil deposit will reach the surface ina detectable form, it has now been found according to this inven-Patented Nov. 15, 1966 tion, that certain of such trace constituents doin fact reach the surface in a readily detectable form and permit anaccurate and economical method of plotting the entire extent of the oilfield without the annular anomaly which resulted from many priorprospecting methods. Amongst such detectable trace constituents areorgano-metallic compounds including for example the volatile metallicporphyrins which are carried upwardly with the liquid and gaseous oilescaping from the oil deposit, and, on reaching oxidation zone at thesurface, or near surface, become oxidized and can be detected asorgano-metallic compounds present in the soil. Such organo-metalli-ccompounds and their derivatives and oxidation products can also bedetected in other media, such as, stream, lake or marine sediments,surface and ground water, and in rock formations both on the surface andin subsurface areas.

In addition to the foregoing, the invention also comprehends theisolation and analysis of oxidation and a1- teration products of thehydrocarbons themselves caused by the action of the micro-organisms andthe oxidation conditions thereon, since this also will afford a methodof procuring a continuous anomaly rather than a fringe anomaly at ornear the surface.

It is therefore a principal objective of the invention to provide ageochemical method for detecting the presence of oil, gas and bituminousdeposits by sampling techniques which is both simple and economical tooperate and which is eflicient and reliable in use.

More-particularly, it is an objective of the invention to provide ageochemical method having the foregoing advantages which is sensitiveover substantially all areas of the oil deposit and in areas remote fromthe deposit.

More particularly, it is an object of this invention to provide ageochemical method having the foregoing advantages which is adaptable tooperation on a wide variety of surface materials including soil, Water,rock and stream, lake and marine sediment.

More particularly, it is an object of the invention to provide a methodhaving the foregoing advantages which is capable of indicating the classof oil deposit present.

The invention seeks to achieve the foregoing and other advantages whichwill become apparent from the following description of a preferredembodiment by the provision of the method of detecting the presence ofoil, gas and bituminous deposits by sampling from the surface of theearth and comprising: obtaining at least one earth surface sample;treating said sample to separate therefrom any oxidation and alterationproducts and trace elements of said deposits; and determining theproportions of said products and elements present in said sample.

A preferred embodiment of the invention will now be described by way ofexample only in order to illustrate the invention.

According to this preferred form of the invention, samples are takenmanually or mechanically at equally spaced intervals along apredetermined traverse line and are isolated from one another and markedaccording to their location. Such samples are preferably taken from theA or B lithological soil horizons wherein oxidizing conditions arepresent. The samples are then air dried in the laboratory and arepreconcentrated by sieving in a mesh of approximately 200 B.S.F. or lesssufficient to pass clays, silts and very fine sands and to discard theresidue.

An accurately measured portion of each sample is then treated with anorganic solvent such as benzene, petroleum ether, carbon tetrachloride,carbon disulphide, or any other organic solvent adapted to dissolvepetroleum and its derivatives. The mixture is then treated with an acid,for example, sulphuric acid, hydrochloric acid, or the like, in order toseparate the oxidation and alteration products and trace elements of theoil deposit from the remainder of the sample, and to cause the organicconstituents thereof to enter into solution in the organic solvents. Themixture is then emulsified hy agitation or ultrasonic means. The mixtureis then separated into three phases, solid, acid and organic solventphase, by centrifuging. The two phases are then separately analyzed andthe results are plotted in the sequence of sampling along the traverseline. It will be understood that the analysis in each case is directedto the quantitative determination of the organic and alteration productsand trace elements of the oil deposit. Thus, in the case of the organicphase, the analysis is directed towards the metals originating in theorgano-metallic compounds and towards the other diagnostic oxidationproducts of hydrocarbons, and in the case of the acid phase is directedtowards socalled leachable metals or more loosely chemically bonded with5 ml. of benzene analog grade and mixed thoroughly. The sample andorganic solvent was then treated with 10 ml. of five normal hydrochloricacid and mixed thoroughly. The mixture was then emulsified by ultrasonictreatment and subsequently centrifuged at 3000 r.p.m. to

separate out the solid, acid, and organic phases respec- The threephases were then placed in separate conmetals present in the earthssurface in the zone of reduc- The following results were obtained:

Results [Figures are for parts per billion of nickel in sample; 120 isbackground] A B C D E F G H I J K L M N O Benzene Soluble Nickel 120 120120 1, 200 6, 000 3, 600 3, 600 3, 600 120 120 120 120 120 120 120 AcidSoluble Nickel 1, 000 1, 000 5, 000 5, 000 3, 000 2, 000 1, 000 7, 00010, 000 1, 000 1, 000 1, 000 1, 000 1, 000 1, 000 Total Nickel inUntreated Sample 15, 000 15, 000 15,000 15, 000 15, 000 15,000 15, 00015,000 15,000 15, 000 15,000 15, 000 15,000 15,000 15, 000

ing hydrocarbon gases escaping around the fringe of the deposit. Thelatter acid phase analysis will of course result only in an annularanomaly of the type already observed, while the organo phase analysiswill result in a continuous anomaly co-extensive with the limits of theannular anomaly. It will be apparent that the above steps constitute arelatively simple and economical method of analysis which mayadvantageously be carried on, for example, by one man at the rate ofapproximately a hundred samples or more per day, as compared with priorgeochemical methods in which four to ten samples a day was about themaximum that could be achieved, and which used complicated and expensiveequipment.

It will also be noted that the above method is readily adaptable to thedetection of oxidation and alteration products and trace elements of oildeposits carried in sediments of streams, lakes and seas and in surfaceand ground water and also in rock formations.

By way of illustration, a description will now be given of a specifictest conducted over a known oil deposit.

EXAMPLE 1 A traverse line was established across the oil deposit andextending beyond both peripheries thereof. Portions of soil were thenremoved along the traverse line at intervals of seventeen hundred feetfrom the A l lithological soil horizon, in that locality, being situatein about the top six inches of the earths surface. Each portion wasplaced in a separate container and successively marked A, B, C, D, E, F,G, H, I, J, K, L, M, N, 0, respectively.

Portions A, B and C were known to be outside the limits of the oildeposit.

Portions D, E, F, G and H were known to be taken within the limits ofthe oil deposit and substantially vertically above it.

Portions I, J, K, L, M, N and 0 were taken beyond the further limits ofthe oil deposit, all of these portions being, as stated, on a straighttraverse line.

In the laboratory each portion was air dried and sieved to separatematerial below 200 mesh, the remaining material being discarded. Fromeach portion a sample of .five grams of sieved material was removed andwas treated Other metals showed a similar dispersion pattern.

The method also applies to other oxidation products of petroleum andalso to alteration products thereof.

While there has been described what is at present considered a preferredembodiment of the present invention, it will be appreciated by thoseskilled in the art that various changes and modifications can be madetherein without departing from the essence of the invention and it isintended to cover herein all such changes and modifications as comewithin the true spirit and scope of the appended claims.

What I claim is:

l. The method of detecting the presence of oil, gas and bituminousdeposits by sampling from the surface of the earth and comprising:

(a) obtaining a series of earth surface samples from spaced locations;

(b) treating said samples to separate therefrom any organo-metalliccompounds of said deposits;

(c) determining the proportions of said compounds present in saidsample;

(d) and plotting said proportions in relation to said locations.

2. The method of detecting the presence of oil, gas and bituminousdeposits by shallow surface soil sampling and comprising:

(a) obtaining a series of soid samples selected from soil lying in the Aand B lithological soil horizons at special locations;

(b) treating said samples to separate therefrom any organo-rnetalliccompounds present therein and maintain the same in solution;

(0) testing said solution to determine the quantities of metals therein;

(d) and plotting said proportions in relation to said locations of saidsamples.

3. The method of detecting the presence of oil, gas and bituminousdeposits by shallow surface soil sampling and comprising:

(a) obtaining a series of soil samples selected from soil lying in the Aand B lithological soil horizons at special locations;

(b) treating said samples with an organic solvent to separate therefromany organo-metallic compounds present therein and obtain solutionsthereof in said solvent;

(0) testing said solution to determine the quantities of metals therein;

((1) and plotting said quantities in relation to respective locations ofsaid samples.

4. The method of detecting the presence of oil, gas and bituminousdeposits by shallow surface soil sampling and comprising:

(a) obtaining a series of soil samples at spaced locations selected fromsoil lying in the A and B lithological soil horizons;

(b) treating said samples with an acid in the presence of an organicsolvent to separate therefrom any organo-metallic compounds presenttherein and obtain solutions of said compounds in said organic solvent;

(0) testing said solutions to determine the quantities of metalstherein;

(d) and plotting said quantities in relation to the respective locationsof said samples.

5. The method of detecting the presence of oil, gas and bituminousdeposits by shallow surface soil sampling and comprising:

(a) establishing a traverse line;

(b) obtaining a series of earth surface soil samples from locationsspaced apart along said traverse line;

(0) treating said samples to separate therefrom any oxidation andalteration products of trace elements of said deposits;

(d) determining the proportions of said-products present in saidsamples;

(e) and plotting said proportions against respective locations on saidtraverse line to establish a single continuous sequence of sampleshaving higher proportions between sequences of samples having lowerproportions.

6. The method of detecting the presence of oil, gas and bituminousdeposits by shallow surface soil sampling an comprising:

(a) establishing a traverse line;

(b) obtaining a series of earth surface soil samples from locationsspaced apart along said traverse line, said samples being selected fromsoil lying in the A and B lithological soil horizons;

(c) treating said samples to separate therefrom any oxidation andalteration products of trace elements of said deposits;

((1) determining the proportions of said products present in saidsamples;

(e) and, plotting said proportions against respective locations on saidtraverse line to establish a single continuous sequence of sampleshaving higher proportions between sequences of samples having lowerproportions.

7. The method of detecting the presence of oil, gas and bitmuinousdeposits by shallow surface soil sampling and comprising:

(a) establishing a traverse line;

(b) obtaining a series of earth surface soil samples from locationsspaced apart along said traverse line;

(c) treating said samples with an acid in the presence of an organicsolvent to separate therefrom any organometallic compounds presenttherein and obtain a solution thereof in said solvent;

(d) determining the proportions of said organo-metallic compoundspresent in said samples;

(e) and, plotting said proportions against respective locations on saidtraverse line to establish a single continuous sequence of sampleshaving higher proportions between sequences of samples having lowerproportions.

8. The method of detecting the presence of oil, gas and bituminousdeposits by shallow surface soil sampling and comprising:

(a) establishing a traverse line;

(b) obtaining a series of earth surface soil samples from locationsspaced apart along said traverse line;

(0) treating said samples with an organic solvent to separate therefromany organo-metallic compounds present therein;

(d) treating said samples in said solvent with an acid to obtain asolution of said organo-metallic compounds in said organic solvent;

(e) determining the proportions of said organo-metallic compoundspresent in said samples;

(f) and, plotting said proportions against respective locations on saidtraverse line to establish a single continuous sequence of sampleshaving higher proportions between sequences of samples having lowerporportions.

References Cited by the Examiner UNITED STATES PATENTS 2,310,291 2/ 1943Horvitz 23230 2,451,883 10/ 1948 Squires 23--230 2,470,401 5/ 1949Horvitz 23-230 MORRIS O. WOLK, Primary Examiner.

D. GANTZ, J. H. TAYMAN, JR., Assistant Examiners.

1. THE METHOD OF DETECTING THE PRESSURE OF OIL, GAS AND BITUMINOUS DEPOSITS BY SAMPLING FROM THE SURFACE OF THE EARTH AND COMPRISING: (A) OBTAINING A SEROES OF EARTH SURFACE SAMPLES FROM SAPCED LOCATIONS; (B) TREATING SAID SAMPLES TO SEPARATE THEREFROM ANY ORGANO-METALLIC COMPOUNDS OF SAID DEPOSITS; (C) DETERMINING THE PROPORTIONS OF SAID COMPOUNDS PRESENT IN SAID SAMPLE; (D) AND PLOTTING SAID PROPORTIONS IN RELATION TO SAID LOCATIONS. 